From 1cc1e3749df6ccefb741232d7949fd5893d84f66 Mon Sep 17 00:00:00 2001
From: Eugene Bujak <hmage@hmage.net>
Date: Thu, 4 Oct 2018 13:38:52 +0300
Subject: [PATCH] dnsfilter -- lazily initialize safebrowsing and parental
 lookup cache

---
 dnsfilter/dnsfilter.go | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/dnsfilter/dnsfilter.go b/dnsfilter/dnsfilter.go
index b40d6a38..41ca687e 100644
--- a/dnsfilter/dnsfilter.go
+++ b/dnsfilter/dnsfilter.go
@@ -130,8 +130,8 @@ const (
 // these variables need to survive coredns reload
 var (
 	stats             Stats
-	safebrowsingCache = gcache.New(defaultCacheSize).LRU().Expiration(defaultCacheTime).Build()
-	parentalCache     = gcache.New(defaultCacheSize).LRU().Expiration(defaultCacheTime).Build()
+	safebrowsingCache gcache.Cache
+	parentalCache     gcache.Cache
 )
 
 // Result holds state of hostname check
@@ -551,6 +551,9 @@ func (d *Dnsfilter) checkSafeBrowsing(host string) (Result, error) {
 		}
 		return result, nil
 	}
+	if safebrowsingCache == nil {
+		safebrowsingCache = gcache.New(defaultCacheSize).LRU().Expiration(defaultCacheTime).Build()
+	}
 	result, err := d.lookupCommon(host, &stats.Safebrowsing, safebrowsingCache, true, format, handleBody)
 	return result, err
 }
@@ -594,6 +597,9 @@ func (d *Dnsfilter) checkParental(host string) (Result, error) {
 		}
 		return result, nil
 	}
+	if parentalCache == nil {
+		parentalCache = gcache.New(defaultCacheSize).LRU().Expiration(defaultCacheTime).Build()
+	}
 	result, err := d.lookupCommon(host, &stats.Parental, parentalCache, false, format, handleBody)
 	return result, err
 }
@@ -781,7 +787,9 @@ func New() *Dnsfilter {
 // Destroy is optional if you want to tidy up goroutines without waiting for them to die off
 // right now it closes idle HTTP connections if there are any
 func (d *Dnsfilter) Destroy() {
-	d.transport.CloseIdleConnections()
+	if d != nil && d.transport != nil {
+		d.transport.CloseIdleConnections()
+	}
 }
 
 //